Tracker systems may be used to provide orientation and/or location data relating to a frame of reference, most typically as a function of time. Tracker systems can be self-contained within a moving subsystem (e.g., inertial trackers) or they can be spread across multiple frames of reference (e.g., optical, magnetic, acoustic, ultrasonic, mechanical, outside-in, inside-out). Exemplary tracker applications include navigation, remote monitoring, head-worn displays, guided munitions, simulators, device/computer input devices including the mouse, trackball, and gesture recognition. Multiple trackers may also be used together for redundancy, truthing, drift correction, or the like. In the case of inertial trackers, dual tracker systems may be compared to extract motion (translational and/or rotational) of a tracked object relative to a moving platform. In many cases, multiple relationships are stacked, one upon another, to yield a composite relation. One such example would be tracking an aircraft relative to the earth, calibrating or tracking a flight deck instrument relative to the aircraft, and tracking a head-worn display relative to the flight deck instrument.
Tracking the location and orientation of a head-worn display is a key aspect to providing meaningful information for certain display applications, such as displaying imagery that is conformal with the forward scene, and that is visible through optics that include a combiner element. Ideally, both a head-worn display and its associated tracker system would be small, lightweight, highly accurate, repeatable, very fast (i.e., high update rate with low latency) and low cost. Although an inertial tracker provides many of these characteristics and benefits, use of compact inertial trackers can also introduce tradeoffs in terms of accuracy, leading to inertial tracker output drift over time.
Accordingly, it is desirable to provide a system that also incorporates detection and correction of inertial tracker output drift. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.